Is there any way to upgrade my G4 iBook to use in some viable way in 2013?

Hello,

If your iBook is above 800mhz, you can upgrade to Mac OS X 10.5 Leopard.

To do so will require at least 512meg of memory and the retail DVD.

The DVD can be brought from places like eBay or Amazon.

Be aware that if you upgrade the Mac OS X beyond 10.4.11 you will lose the ability to use Classic Environment. You can download the 10.4.11 combo update.

http://support.apple.com/kb/TA24901

http://support.apple.com/downloads/Mac_OS_X_10_4_11_Combo_Update__PPC_

There are ways to make web browsing more enjoyable as are noted on this thread.